Schapelle Corby speaks for the first time in world's shortest radio interview.

Four days on from returning to Australia, Schapelle Corby has mustered a ‘hello’ on live radio.

Speaking to Kyle Sandilands and Jackie O from their hideout on Wednesday morning, Mercedes Corby, who spoke at length with the radio hosts, confirmed, “Schapelle’s here with me,” before Sandilands asked for “proof of life.”

Jackie O's response to hearing Schapelle Corby. Image via Twitter.

After some coercing from her sister, 39-year-old Schapelle came to the phone and simply said, "hello," before handing the interview back to Mercedes.

"She's shy," Mercedes explained.

During the 10-minute-long interview, Mercedes confirmed that the family are "very happy" to have Schapelle back and said her sister is doing really well.

"We're just letting her relax, she can figure it out as time goes by," Mercedes said, adding that Schapelle still needs "time to relax; find herself."

When asked about her sister's plans for the future and what she hopes to do with her life, Mercedes was noncommittal in her answers but confirmed that despite previous media reports, Schapelle will be allowed back into Bali - which could signal a reunion with her boyfriend.

Kyle Sandilands' response to hearing Schapelle Corby. Image via Twitter.

When the KIIS FM presenters asked what that means for Schapelle's relationship with Balinese local Ben Panangian - who the convicted drug smuggler was dating throughout her three-year parole period, Mercedes simply replied, "I'm not really sure but that's another thing.

She later added, "it's too early for her to make any decisions."